It is a rare event when new and useful medical parameters can be added to the suite of monitoring and diagnostic tests available in a clinical setting. Of particular importance is the ability to measure crucial physiological parameters or analyses in a continuous and noninvasive manner-evidenced by the importance of noninvasive vital signs monitoring-because it reduces expense, eliminates delays in diagnosis, and removes the potential for exposure to blood-borne pathogens. The project for which this SBIR Grant proposal is being submitted will continue the work towards a new patient monitor capable of accurate, noninvasive, and continuous measurements of total hemoglobin (the). The measurement of total hemoglobin is a crucial and frequently performed blood test used in nearly all areas of healthcare. The accurate measurement of this parameter is particularly important for patients potentially requiring a transfusion, receiving rapid administration of fluids, undergoing surgical procedure, or having experienced trauma that has resulted in significant blood loss. Total hemoglobin must also be measured for anemia screening prior to blood donation. The proposed new monitor would look much like conventional pulse dosimeter, the ubiquitous vital- signs monitor that has been in clinical use since the 1980s and which uses a clothespin-like sensor to shine red and infrared light through the finger and report a measure of the oxygen level in the arterial blood. And, in fact, the ultimate goal of the product development effort that would follow this feasibility study will be the integration of total-hemoglobin-measuring capabilit into a pulse dosimeter. Successful completion of the proposed grant work will complete the next important steps towards the creation of this new medical monitor. This work will prove that the high measurement precision provided by the use of narrow-band lasers can make possible accurate noninvasive measurement of the on human subjects over a clinically-relevant the range. The continuation of this work into the development of a full commercial version will then lead to a regulatory submission for FDA 510(k) clearance to allow the marketing and sale of this device to the medical community. Availability of a noninvasive total hemoglobin monitor will help diagnose anemic patients sooner and contribute to the judicious use of blood transfusions, all with less pain or risk of infection while reducing the time burden on caregivers and costs to the healthcare system. It could also eliminate the need for the somewhat painful finger sticks associated with blood donation.